Serial-link I/O interconnect protocols, such as PCI-Express, are utilized in computing and communication platforms and systems to interconnect components of the platforms to enable efficient I/O transfers between the components. In many instances, it is necessary to transmit data packets from a root complex of the system to multiple internal clients of the system over the serial link. Likewise, it is necessary to transmit data packets from the multiple internal clients of the system to the root complex. Since the speed and efficiency with which the system can operate depends on the effective and efficient transfer of data packets through the system, it is necessary to arbitrate the transfers to give higher priority to certain of the types of data transfers.